1. Technical Field
The present invention relates to a process for manufacturing a semiconductor device.
2. Related Art
In a semiconductor device such as, for example, chip scale package (CSP) and the like, which includes an external connector terminal to be connected to a base substrate which is formed in a side of a circuit surface of a semiconductor chip where the whole semiconductor chip is not covered with a plastic package, a marking surface of the CSP is a surface of the semiconductor chip opposite to the circuit surface thereof, or in other words a back surface of the semiconductor chip.
In such back surface of the chip of such semiconductor device, markings indicating information such as a name of a product, an index mark, a date of manufacture, a lot number, characteristic rank or the like are made by utilizing ink, laser beam or the like. In recent years, a laser marking process becomes mainstream for the marking process, because of improved productivity and the recent trend of concern for the environment, and a need for such laser marking process, which achieves less damage to the semiconductor substrate and better visibility, is increased.
Japanese Patent Laid-Open No. 2001-44,304 describes an enhancement of visibility for marked letters by pre-coating a resin film over a back surface of a semiconductor wafer serving as a marking surface via a spin coating process and partially baking such resin film by laser beam to achieve a marking. Japanese Patent Laid-Open No. 2001-44,304 also describes that laser beam partially reaches the metal portion through the resin film during the cutting with a laser beam.
Japanese Patent Laid-Open No. 2004-311,552 discloses that a mark is formed in a second principal surface opposed to a surface for forming an electrode in a semiconductor device via an etching process without employing laser beam and then a transparent resin layer is formed over the second principal surface and an upper surface of the marking.
However, the present inventor has found that the technology described in Japanese Patent Laid-Open No. 2001-44,304 causes a deterioration of a function for the protective film because the mark is made on the protective film, and also causes a deterioration of the mark because the mark is exposed. Further, the technology also causes a dusting and a generation of exothermic heat from the protective film during the marking process, causing problems of damaging the peripheral protective films or devices. On the other hand, since the technology described in Japanese Patent Laid-Open No. 2004-311,552 involves forming the marking via the etching process, an additional operation for forming an etching mask is required.